1. Field of the Invention
The invention relates to a helical compression spring designed as a thermoplastic molding and having an end collar on the valve-seat side and an end collar on the actuating side.
Such a helical compression spring is used in pumps for hygienic and cosmetic preparations, such as pump sprays.
Upon actuation of a plunger, the helical compression spring is loaded and the preparation is forced out or sprayed. As a result, a valve closure member held in the end collar on the valve-seat side is pressed onto the valve seat to prevent the preparation from flowing back. The valve closure member is normally a steel ball. Even if high-grade steel balls are used, corrosion due to the strongly basic preparations cannot be ruled out. In particular, discoloration may occur.
2. Description of the Prior Art
DE 295 04 817 U describes a helical compression spring at whose end on the valve-seat side a valve closure cap is molded on. The molded-on part is admittedly designed to be movable. However, it inhibits and hinders the movement of the valve closure member.